I hear over and over again that a Chevy 3500/4500 and the Ford E350/E450 chassis with the
LIQUID SPRING (link to the E450 version) package is the ultimate solution for a truly quality ride in a conventional class-C. But the cost of $10,000-$12,000 is where the problem lies. Being a complex system, I wonder how reliable it is over the long haul.
I never drove a rig with Liquid Spring, but I read of people who have. They are so impressed that they spend that much money for it.
A few RV manufactures offer it as an option, but in most cases, you buy the rig, then drop it off yourself at Liquid Spring.